Chicago R&B superstar R. Kelly sang at the Olympics on Friday night amid a growing controversy about a videotape that appears to show him having sex with an underage girl.

In an interview with WMAQ-Channel 5 before the nationally televised performance, Kelly denied any wrongdoing and accused people from his past of trying to ruin his big night at the opening ceremonies in Salt Lake City.

He was responding to questions about the tape, which was sent to the Chicago Sun-Times and showed what looked to be him having sex with a 14-year-old girl. The Sun-Times turned it over to Chicago police, who are investigating. A story about the situation appeared in Friday’s editions.

“It’s not true,” said Kelly, 35.

“All I know is this: I have a few people in the past that I’ve fired . . . people that I’ve thought were my friends that’s not my friends,” he said.

“It’s crap, and that’s how we’re going to treat it.”

As Kelly defended himself, a Chicago lawyer who has filed two civil suits against Kelly claiming that he had sex with underage girls said the family of the girl pictured in the video had contacted her. She is now 17.

“We have been contacted by them over a week ago. I’ve had discussions with the family,” said Susan E. Loggans, the lawyer representing Tiffany Hawkins and Tracy Sampson, who claim they were 15 and 17, respectively, when Kelly had sex with them. “I think the whole thing is coming out, which is probably healthy.”

Illinois law prohibits adult men from having sex with girls under 17. It is a felony to videotape a sexual act with anyone under 18, prosecutors said.

Kelly, whose attorney said the tape is a fake, says people with whom he once associated are out to get him. “The reason these things are happening I really do believe is because of the fact that I didn’t fall back as far as blackmail was concerned,” Kelly said. “I didn’t give them any money.”

He said he was speaking out because “I feel like I owe my fans” an explanation.

“The world is getting ready to watch me sing a song called “The World’s Greatest,” and you’ve got a tape out there trying to ruin my career,” he said.

Robert S. Kelly is the most successful R&B performer from Chicago in the last 30 years. He has sold more than 20 million albums, and he scored a worldwide hit with the 1997 single “I Believe I Can Fly.”